The results are not only relevant for understanding wildlife, but also have potential applications for drone-flying strategies and in the entertainment industry.
The researchers, Milán Janosov, Csaba Virágh, Gábor Vásárhelyi, and Tamás Vicsek at the MTA-ELTE Statistical and Biological Physics Research Group, Hungary, have published their paper on their new model of collective chasing strategies in a recent issue of the New Journal of Physics.
"After many previous efforts, we managed to give a simple, yet surprisingly life-like explanation of how predator animals can form successful hunting packs, and by that drastically enhance their chances of being successful on a hunt," Janosov told Phys.org. "This is particularly interesting because we managed to model these exceptionally complex systems—the hunting groups of large carnivores—in a simulation resembling realistic features of animal pursuits, such as encircling, optimal group size, and finite space, only by using a set of compact rules formulated as force-like interactions in physics."
Although there are other models that describe predator-prey interactions, the new model is different because of the large number of factors it accounts for, such as the prey's panic threshold, the predator's ability to predict the prey's future position, and the interaction between multiple predators, within closed boundaries with realistic measures. All of these parameters contribute to making a more realistic model that accurately describes behaviors observed in nature by groups of predators such as lions, wolves, and coyotes.
By running simulations and measuring the effectiveness of different combinations of parameter values, the researchers determined the optimal combinations that resulted in the most successful group chasing strategies. Among their results, they found that just one or two predators can never catch a faster prey, and that groups of three or more succeed only with certain collaborative strategies.
The model revealed that three predators forms an optimal group when chasing in two dimensions (such as on land) in a confined space. In three dimensions (such as in the air or under water), chasing becomes more challenging, and groups of five are optimal. These group sizes are comparable to those observed in nature. Somewhat surprisingly, the researchers also found that an odd number of chasers does better than an even number, which is due to geometrical reasons: with an even number, it's more likely that a gap remains between predators that allows the prey to escape.
In their model, the researchers also observed emergent behavior, which is behavior that appears only in groups. In particular, groups of predators often begin to encircle their prey, and this behavior arises directly from the chasing rules.
In nature, it's common for prey to sometimes run in a zigzag pattern to confuse the predator, and to eventually run directly away from the predator in a straight line. The researchers also observed these strategies in their model, and found that zigzagging is especially advantageous when the predators have a long delay in responding.
In the future, the researchers expect that additional interesting results can be obtained by modifying the model, such as investigating situations with multiple fast prey and equipping predators and prey with machine learning algorithms.
"Our major goal in this research was to gain a deeper understanding of the collective behavior of animals, to extend our knowledge on fundamental questions on animal behavior," Janosov said. "However, given the fact that our research group is developing collective motion algorithms for our flock of quadrocopters, there are plenty of potential applications we could propose. For example, a group of tactical drones using smart encircling strategies could become even lifesaving in the case of terrorist attacks, when the goal is to capture terrorist flying vehicles, or chasing criminals in narrow, highly populated urban areas.
"Besides these, our results could have potential applications even in the entertainment industry in developing field games, possibly combined with virtual reality tools, or by the streaming of popular sport events, especially those that are widely spread in space—for example, bike or car races."
Explore further: Modelling explains how hunters team up to catch faster prey
More information: Milán Janosov et al. "Group chasing tactics: how to catch a faster prey." New Journal of Physics. DOI: 10.1088/1367-2630/aa69e7

If it seems like your dog understands what you’re saying – it’s because they do. Not only do dogs understand some of what people say, they also understand how they’re saying it, using the same regions of the brains as humans to understand vocabulary and intonation, according to a new Science study.
A team led by Attila Andics of Department of Ethology and MTA-ELTE Comparative Ethology Research Group at Eötvös Loránd University, in Budapest, trained 13 dogs to lay still in an fMRI brain scanner as they listened to their trainers speech.
The team recorded brain activity as the dogs listened to different combinations of words, including praise words said with a neutral inflection or praising tone, and also neutral or meaningless words in neutral and praising tones.
The scans showed that like humans, the left hemisphere of the brain was activated in dog brains to process meaningful but not meaningless words. Auditory regions in the right hemisphere of the brain were activated in the dogs’ brains when distinguishing between praising and non-praising words. Interestingly, the dog’s reward center was only activated when they heard a praising word in a praising tone, meaning they could tell the difference between what humans say and how it was said, and combine the information to correctly give meaning to the words.
“During speech processing there is a well-known distribution of labor in the human brain. It is mainly the left hemisphere’s job to process word meaning, and the right hemisphere’s job to process intonation,” Andics said in a prepared statement. “The human brain not only separately analyzes what we say and how we say it, but also integrates the two types of information, to arrive at a unified meaning. Our findings suggest that dogs can also do all that they use very similar brain mechanisms.”
The Hungarian research team said the findings suggest that the brain mechanisms needed to process words are not unique to humans and evolved much earlier than previously thought. While other animals are not able to invent words, they still have the ability to understand and give meaning to them.
“Our research sheds new light on the emergence of words during language evolution,” Andics said. “What makes words uniquely human is not a special neural capacity, but our invention of using them.”
The findings were published Sept. 2 in Science.

The findings of a Hungarian research group suggest that the neural mechanisms to process words evolved much earlier than previously thought, and they are not unique to the human brain, the researchers say. It shows that if an environment is rich in speech, as is the case of family dogs, word meaning representations can arise in the brain, even in a non-primate mammal that is not able to speak.
"During speech processing, there is a well-known distribution of labor in the human brain. It is mainly the left hemisphere's job to process word meaning, and the right hemisphere's job to process intonation. The human brain not only separately analyzes what we say and how we say it, but also integrates the two types of information, to arrive at a unified meaning. Our findings suggest that dogs can also do all that, and they use very similar brain mechanisms," said lead researcher Attila Andics of Department of Ethology and MTA-ELTE Comparative Ethology Research Group at Eötvös Loránd University, Budapest.
"We trained thirteen dogs to lay completely motionless in an fMRI brain scanner. fMRI provides a non-invasive, harmless way of measurement that dogs enjoy to take part of," said Márta Gácsi, ethologist, the developer of the training method, author of the study. "We measured dogs' brain activity as they listened to their trainer's speech," explains Anna Gábor,
PhD student, author of the study. "Dogs heard praise words in praising intonation, praise words in neutral intonation, and also neutral conjunction words, meaningless to them, in praising and neutral intonations. We looked for brain regions that differentiated between meaningful and meaningless words, or between praising and non-praising intonations."
The brain activation images showed that dogs prefer to use their left hemisphere to process meaningful but not meaningless words. This left bias was present for weak and strong levels of brain activations as well, and it was independent of intonation. Dogs activate a right hemisphere brain area to tell apart praising and non-praising intonation. This was the same auditory brain region that this group of researchers previously found in dogs for processing emotional non-speech sounds
from both dogs and humans, suggesting that intonation processing mechanisms are not specific to speech.
Andics and colleagues also noted that praise activated dogs' reward center – the brain region which responds to all sorts of pleasurable stimuli, like food, sex, being petted, or even nice music in humans. Importantly, the reward center was active only when dogs heard praise words in praising intonation. "It shows that for dogs, a nice praise can very well work as a reward, but it works best if both words and intonation match. So dogs not only tell apart what we say and how we say it,
but they can also combine the two, for a correct interpretation of what those words really meant. Again, this is very similar to what human brains do," Andics said.
This study is the first step to understanding how dogs interpret human speech, and these results can also help to make communication and cooperation between dogs and humans even more efficient, the researchers say.
These findings also have important conclusions about humans. "Our research sheds new light on the emergence of words during language evolution. What makes words uniquely human is not a special neural capacity, but our invention of using them," Andics explains.
Explore further: Dogs know a left-sided wag from a right
More information: Neural mechanisms for lexical processing in dogs, Science, science.sciencemag.org/cgi/doi/10.1126/science.aaf3777

People have a remarkable ability to remember and recall events from the past, even when those events didn't hold any particular importance at the time they occurred. Now, researchers reporting in the journal Current Biology on November 23 have evidence that dogs have that kind of "episodic memory" too.
The study found that dogs can recall a person's complex actions even when they don't expect to have their memory tested.
"The results of our study can be considered as a further step to break down artificially erected barriers between non-human animals and humans," says Claudia Fugazza of MTA-ELTE Comparative Ethology Research Group in Budapest, Hungary. "Dogs are among the few species that people consider 'clever,' and yet we are still surprised whenever a study reveals that dogs and their owners may share some mental abilities despite our distant evolutionary relationship."
Evidence that non-human animals use episodic-like memory has been hard to come by because you can't just ask a dog what it remembers. In the new study, the researchers took advantage of a trick called "Do as I Do." Dogs trained to "Do as I Do" can watch a person perform an action and then do the action themselves. For example, if their owner jumps in the air and then gives the "Do it!" command, the dog would jump in the air too.
The fact that dogs can be trained in this way alone wasn't enough to prove episodic memory. That's because it needed to be shown that dogs remember what they just saw a person do even when they weren't expecting to be asked or rewarded. To get around this problem, the researchers first trained 17 dogs to imitate human actions with the "Do as I Do" training method. Next, they did another round of training in which dogs were trained to lie down after watching the human action, no matter what it was.
After the dogs had learned to lie down reliably, the researchers surprised them by saying "Do It" and the dogs did. In other words, the dogs recalled what they'd seen the person do even though they had no particular reason to think they'd need to remember. They showed episodic-like memory.
Dogs were tested in that way after one minute and after one hour. The results show they were able to recall the demonstrated actions after both short and long time intervals. However, their memory faded somewhat over time.
The researchers say that the same approach can most likely be used and adapted in a wide range of animal species, to better understand how animals' minds process their own actions and that of others around them.
"From a broad evolutionary perspective, this implies that episodic-like memory is not unique and did not evolve only in primates but is a more widespread skill in the animal kingdom," Fugazza says. "We suggest that dogs may provide a good model to study the complexity of episodic-like memory in a natural setting, especially because this species has the evolutionary and developmental advantage to live in human social groups."
For all those dog owners out there: your dogs are paying attention and they'll remember.

The study found that dogs can recall a person's complex actions even when they don't expect to have their memory tested.
"The results of our study can be considered as a further step to break down artificially erected barriers between non-human animals and humans," says Claudia Fugazza of MTA-ELTE Comparative Ethology Research Group in Budapest, Hungary. "Dogs are among the few species that people consider 'clever,' and yet we are still surprised whenever a study reveals that dogs and their owners may share some mental abilities despite our distant evolutionary relationship."
Evidence that non-human animals use episodic-like memory has been hard to come by because you can't just ask a dog what it remembers. In the new study, the researchers took advantage of a trick called "Do as I Do." Dogs trained to "Do as I Do" can watch a person perform an action and then do the action themselves. For example, if their owner jumps in the air and then gives the "Do it!" command, the dog would jump in the air too.
The fact that dogs can be trained in this way alone wasn't enough to prove episodic memory. That's because it needed to be shown that dogs remember what they just saw a person do even when they weren't expecting to be asked or rewarded. To get around this problem, the researchers first trained 17 dogs to imitate human actions with the "Do as I Do" training method. Next, they did another round of training in which dogs were trained to lie down after watching the human action, no matter what it was.
After the dogs had learned to lie down reliably, the researchers surprised them by saying "Do It" and the dogs did. In other words, the dogs recalled what they'd seen the person do even though they had no particular reason to think they'd need to remember. They showed episodic-like memory.
Dogs were tested in that way after one minute and after one hour. The results show they were able to recall the demonstrated actions after both short and long time intervals. However, their memory faded somewhat over time.
The researchers say that the same approach can most likely be used and adapted in a wide range of animal species, to better understand how animals' minds process their own actions and that of others around them.
"From a broad evolutionary perspective, this implies that episodic-like memory is not unique and did not evolve only in primates but is a more widespread skill in the animal kingdom," Fugazza says. "We suggest that dogs may provide a good model to study the complexity of episodic-like memory in a natural setting, especially because this species has the evolutionary and developmental advantage to live in human social groups."
For all those dog owners out there: your dogs are paying attention and they'll remember.
Explore further: Dogs imitate novel human actions and store them in memory
More information: Current Biology, Fugazza et al.: "Recall of Others' Actions after Incidental Encoding Reveals Episodic-like Memory in Dogs" http://www.cell.com/current-biology/fulltext/S0960-9822(16)31142-3 , DOI: 10.1016/j.cub.2016.09.057

People have a remarkable ability to remember and recall events from the past, even when those events didn't hold any particular importance at the time they occurred. Now, researchers reporting in the journal Current Biology on November 23 have evidence that dogs have that kind of "episodic memory" too.
The study found that dogs can recall a person's complex actions even when they don't expect to have their memory tested.
"The results of our study can be considered as a further step to break down artificially erected barriers between non-human animals and humans," says Claudia Fugazza of MTA-ELTE Comparative Ethology Research Group in Budapest, Hungary. "Dogs are among the few species that people consider 'clever,' and yet we are still surprised whenever a study reveals that dogs and their owners may share some mental abilities despite our distant evolutionary relationship."
Evidence that non-human animals use episodic-like memory has been hard to come by because you can't just ask a dog what it remembers. In the new study, the researchers took advantage of a trick called "Do as I Do." Dogs trained to "Do as I Do" can watch a person perform an action and then do the action themselves. For example, if their owner jumps in the air and then gives the "Do it!" command, the dog would jump in the air too.
The fact that dogs can be trained in this way alone wasn't enough to prove episodic memory. That's because it needed to be shown that dogs remember what they just saw a person do even when they weren't expecting to be asked or rewarded. To get around this problem, the researchers first trained 17 dogs to imitate human actions with the "Do as I Do" training method. Next, they did another round of training in which dogs were trained to lie down after watching the human action, no matter what it was.
After the dogs had learned to lie down reliably, the researchers surprised them by saying "Do It" and the dogs did. In other words, the dogs recalled what they'd seen the person do even though they had no particular reason to think they'd need to remember. They showed episodic-like memory.
Dogs were tested in that way after one minute and after one hour. The results show they were able to recall the demonstrated actions after both short and long time intervals. However, their memory faded somewhat over time.
The researchers say that the same approach can most likely be used and adapted in a wide range of animal species, to better understand how animals' minds process their own actions and that of others around them.
"From a broad evolutionary perspective, this implies that episodic-like memory is not unique and did not evolve only in primates but is a more widespread skill in the animal kingdom," Fugazza says. "We suggest that dogs may provide a good model to study the complexity of episodic-like memory in a natural setting, especially because this species has the evolutionary and developmental advantage to live in human social groups."
For all those dog owners out there: your dogs are paying attention and they'll remember.

People have a remarkable ability to remember and recall events from the past, even when those events didn't hold any particular importance at the time they occurred. Now, researchers reporting in the journal Current Biology on November 23 have evidence that dogs have that kind of "episodic memory" too.
The study found that dogs can recall a person's complex actions even when they don't expect to have their memory tested.
"The results of our study can be considered as a further step to break down artificially erected barriers between non-human animals and humans," says Claudia Fugazza of MTA-ELTE Comparative Ethology Research Group in Budapest, Hungary. "Dogs are among the few species that people consider 'clever,' and yet we are still surprised whenever a study reveals that dogs and their owners may share some mental abilities despite our distant evolutionary relationship."
Evidence that non-human animals use episodic-like memory has been hard to come by because you can't just ask a dog what it remembers. In the new study, the researchers took advantage of a trick called "Do as I Do." Dogs trained to "Do as I Do" can watch a person perform an action and then do the action themselves. For example, if their owner jumps in the air and then gives the "Do it!" command, the dog would jump in the air too.
The fact that dogs can be trained in this way alone wasn't enough to prove episodic memory. That's because it needed to be shown that dogs remember what they just saw a person do even when they weren't expecting to be asked or rewarded. To get around this problem, the researchers first trained 17 dogs to imitate human actions with the "Do as I Do" training method. Next, they did another round of training in which dogs were trained to lie down after watching the human action, no matter what it was.
After the dogs had learned to lie down reliably, the researchers surprised them by saying "Do It" and the dogs did. In other words, the dogs recalled what they'd seen the person do even though they had no particular reason to think they'd need to remember. They showed episodic-like memory.
Dogs were tested in that way after one minute and after one hour. The results show they were able to recall the demonstrated actions after both short and long time intervals. However, their memory faded somewhat over time.
The researchers say that the same approach can most likely be used and adapted in a wide range of animal species, to better understand how animals' minds process their own actions and that of others around them.
"From a broad evolutionary perspective, this implies that episodic-like memory is not unique and did not evolve only in primates but is a more widespread skill in the animal kingdom," Fugazza says. "We suggest that dogs may provide a good model to study the complexity of episodic-like memory in a natural setting, especially because this species has the evolutionary and developmental advantage to live in human social groups."
For all those dog owners out there: your dogs are paying attention and they'll remember.
The authors received funding from the MTA-ELTE Comparative Ethology Research Group, and the project received funding from the Hungarian Scientific Research Fund.
Current Biology, Fugazza et al.: "Recall of Others' Actions after Incidental Encoding Reveals Episodic-like Memory in Dogs" http://www.cell.com/current-biology/fulltext/S0960-9822(16)31142-3
Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit: http://www. . To receive Cell Press media alerts, contact press@cell.com.